5566
J . Org. Chem. 1985,50, 5566-5574
conducted a t ambient temperature (24 "C). 1. Neutralization of the THF Nonextractable Component of Illinois No. 6 Coal. A 100-mLsingle-necked, round-bottomed flask was equipped with a magnetic stirring bar and charged with 4.00 g of THF-insoluble Illinois No. 6 coal. The solid coal was stirred and 55.0 mL of 0.26 M KOH (1equiv assuming 3.5 mequiv of acidic hydrogens per gram of coal) in methanol was added in one portion rapidly. When addition of the base solution was completed, a timer was started and the kinetics run begun. During the course of the neutralization, the solution was maintained under a positive pressure of nitrogen. Periodically, the slurry was sampled by using a large bore calibrated glass tube and a Glasfirn "Pi-Pump" pipetting aid. A 2-mL aliquot was removed. Control experiments showed that the slurry was well agitated and that equal portions of coal and solution were removed regardless of the sampling depth of the pipette. The removed aliquot was filtered by using a sintered glass, medium frit filtration funnel. The coal was washed with 2 mL of methanol and the filtrate was
diluted with 20 mL of deionized, degassed water. The aqueous methanol solution was then titrated with 0.020 M HC1 to a pH of 7.0. Blank titrations, without coal, were done to determine the initial base concentration. Final base concentrations in the reaction mixture were determined after 24 h. 2. Base Capacity Measurements. Equilibrium base capacities were measured after 2 weeks by titration of a known volume aliquot removed from the supernatant of the centrifuged swelling samples. The titration was conducted a t room temperature with standard acid solution (0.020 M HC1) using a Beckman Potentiograph (E 536) and a Metrohm (655) Dosimat.
Acknowledgment. We extend special thanks to Professor J. Larsen for insightful discussions and his instrumental contributions to the progress of our work. Appreciation is also given to M. L. Gorbaty, P. S. Hagan, J. S. Gethner, and D. Brenner for valuable suggestions.
w.
Conjugate Addition of Acylate-Nickel Complexes to Quinone Monoketals: Formal Synthesis of the Naphthoquinone Antibiotics Nanaomycin A and Deoxyfrenolicin M. F. Semmelhack,* L. Keller,'* T. Sato, E. J. Spiess,lb and W. WulfflC Department of Chemistry, Princeton University, Princeton, New Jersey 08544 Received August 13, 1985
A direct approach to the synthesis of isochromanone antibiotics such as nanaomycin A (2) and deoxyfrenolicin (3) is the conjugate addition of a carbonyl anion equivalent to the appropriate naphthoquinone monoketal followed by trapping with an allylic halide. This provides a naphthoquinone nucleus with two side chains which are appropriate for the palladium-promoted heterocyclization developed earlier to complete the fused pyrano ring system. As previously observed in related systems, conjugate addition of carbonyl anion equivalents to benzoquinone and naphthoquinone monoketals leads to reductive cleavage as a major pathway, especially with the benzoquinone monoketals. The most general solution to the problem is the Corey-Hegedus procedure for preparation and reaction of acylate-nickel complexes. In the first tests with quinone monoketals, efficient conjugate addition is observed with naphthoquinone monoketals, and the intermediate enolate anions can be trapped with high efficiency by using allyl iodide. Manipulation of the quinone and acyl functionality allows the formation of the a-(hydroxyalky1)naphthoquinonesystem, and the palladium(I1)-catalyzed ring closure gives the desired isochromanone ring system. Use of the acyl-nickel complex from methyllithium and nickel carbonyl provides nanaomycin A (2), while the combination of n-propyllithium and nickel carbonyl leads to deoxyfrenolicin (3) by the same route. Scheme I
Introduction There is a set of natural products that have as common structural features a pyran ring with an alkyl substituent a t C-2 and an acetic acid unit a t C-6, usually trans, and fused to a naphthoquinone unit a t C-3/C-4, as represented and by structure 1. Examples are nanaomycin A (1)(a) Visiting Research Fellow from Department of Chemistry, Florida International University, Miami, FL. (b) NIH Postdoctoral Fellowship Awardee, 1980-1982. (c) NIH Postdoctoral Fellowship Awardee, 1979-1980. (2),(a)Omura, S.; Tanaka, J.; Koyana, Y.; Oiwa, R.; Katagiri, M. J . Antibzot. 1974.25.363.(b) Tanaka. H.: Kovama. Y.: Marumo. H.: Oiwa. R.; Katagiri, hh.;Nagai, T.; Omura; S.'Ibid. 1975,28,860. ( c ) Tanaka; H.; Koyama, Y.; Nagai, T.; Marumo, H.; Omura, S. Ibid. 1975,78,868. (3)For total synthesis efforts, see: (a) Naruta, Y.; Uno, H.; MaruYama, K. Chem. Lett. 1982,609-612. (b) Kometani, T.; Takechi, y.; Yoshii, E. J. Chem. SOC.,Perkin Tram. I 1981,1197-1202.(c) Ichihara, A.; Ubukata, M.; Oikawa, H.; Murakami, K.; Sakamura, S. Tetrahedron Lett. 1980,4469-4477. (d) Kraus, G.A.; Roth, B. J. Org. Chem. 1978,43, 4923-4900. (e) Li, T.;Ellison, R. H. J . Am. Chem. Soc. 1978,100,6263, 6265. (f) Pyrek, J. S.; Achmatowica, O., Jr.; Zamojski, A. Tetrahedron 1977,33,673-680. (8) South, M. S.; Liebeskind, L. J . Am. Chem. SOC. 1984, 106, 4181-4185. (h) Giles, R. G. F.; Green, I. R.; Hugo, V. I.; Mitchell, P. R. K. J . Chem. Soc., Chem. Commun. 1983,51-52.
2 R-Me 3 R:nPr
I CO,H
a
4
ii 0
,
X \ A u-
Sa RZMe 5 b R: nPr
deoxyfrenolicin (3),3r4and more complex members exist. We have been interested in this set of compounds as a testing ground for synthesis methodology, and earlier papers give a more complete i n t r o d ~ c t i o n . ~ (4)Deoxyfrenolicin (1)is a degradation product of a natural epoxy naphthoquinone, frenolicin: Ellestad, G. 2.; Kunstmann, M. P.; Whaley, H. A.; Patterson, E. L. J. Am. Chem. SOC.1968,90,1325.
0022-326318511950-5566$01.50/0 0 1985 American Chemical Society
J. Org. Chem., Vol. 50, No. 26,
Addition of Acylate-Nickel Complexes In this paper we report a study of the Corey-Hegedus procedure for conjugate addition of acylate-nickel complexes: extending the reaction to quinone monoketals (e.g., 4) and including the first trapping procedures for the intermediate enolate using carbon electrophiles.' The process allows particularly direct syntheses of nanaomycin A (2) and deoxyfrenolicin (3) through the key intermediates 5a and 5b (Scheme I). T h e pyran ring would be formed by palladium-promoted alkoxycarbonylation, on the basis of our successful procedure with a closely related system. 5a Conjugate addition of carbonyl anion equivalents to a,P-unsaturated carbonyl compounds is generally possible, of course,@with especially simple examples such as Stetter's thiazolium-catalyzed addition of aldehyde acyl units to acyclic en one^.^ T h e convenient but highly reactive carbon nucleophiles such as the 2-alkyl-1,3-dithianyl system (e.g., 6),1° cyanohydrin acetal anion (e.g., 7)," and
9a
9b
10a
10b
1-lithio-1-[(methoxymethy1)oxylbutane (8)12typically favor 1,2-addition over 1,4-addition. However, the special effect of hexamethylphosphoric triamide (HMPA) in promoting 1,Caddition to simple enones looked promising with these species.13 Quinone monoketals (9, 10) do not behave exactly as simple cyclohexenones; cyanide anion14 and active methylene compounds ( m a l ~ n a t e , cyanoacetate,15 '~ P-keto ester,15 dimethyloxosulfonium methylide16) give efficient conjugate addition a t least with simple substrates such as 9 and 10, but lithiodimethylcuprate gives exclusively reductive cleavage to the hydroquinones monoether (e.g., p-methoxyphenol from 9a)." Survey of Acylate-Nickel Additions to Quinone Monoketals. Our initial studies were carried out on the (5) (a) Zask, A. Ph.D. Thesis, Princeton University, Princeton, NJ, 1982. (b) Semmelhack, M. F.; Zask, A. J.Am. Chem. SOC. 1983,105,2034. (c) Semmelhack, M. F.; Bozell, J. J. Tetrahedron Lett. 1982,2931. (d) Semmelhack, M. F.; Bozell, J. J.; Sato, T.; Wulff, W.; Spies, E.; Zask, A. J. Am. Chem. SOC. 1982,104,5850. (6)(a) Corey, E.J.; Hegedus, L. S. J.Am. Chem. Soc. 1969,91,4926. (b) Hegedus, L. S. Ph.D. Thesis, Harvard University: Cambridge, MA, 1969. (7)A preliminary account of this work has appeared: Semmelhack, M. F.; Keller, L.; Sato, T.; Spiess, E. J. Org. Chem. 1982,47,4382. (8)For a review of reactions of carbonyl anion equivalents, see: Lever, 0. W. Tetrahedron 1976,34, 1943. (9)Stetter, H. Angew. Chem., Znt. Ed. Engl. 1976,15,639. (10)Corey, E.J.; Seebach, D. Angew. Chem., Znt. Ed. Engl. 1965,4, 1075. (11) (a) Stork, G.; Maldonado, L. J. Am. Chem. SOC. 1974,96, 5272. (b) Hunig, S.; Wehner, G. Chem. Ber. 1980,113,324. (12)Still, W. C. J. Am. Chem. Soc. 1978,100,1482. (13)(a) Brown, C. A.; Yamaichi, A. J. Chem. SOC.,Chem. Commun. 1979,100; (b) Still, W. C.; Mitra, A. Tetrahedron Lett. 1978,2659. (c) Lucchetti, J.; Krief, A. Ibid. 1978,2697. (d) Lucchetti, J.; Dumont, W.; Krief Ibid. 1979,2695. (14)Wessely, F. Monatsch. Chem. 1957,88, 228. (15)Parker, K. A.;Kang, S. J. Org. Chem. 1980,45, 1218. Perkin (16)Buchanan, G.L.; Raphael, R. A.; Taylor, R. J.Chem. SOC., Trans. 1973,1,373. (17)Nilsson, A.;Ronlan, A. Tetrahedron Lett. 1975,1107.
1985 5567
quinone ketal 11, from which simple protonation of the
14
16 R:H 11 R:Me
18
expected enolate would produce a useful intermediate related to 5. T h e quinone ketal 11 was prepared in four steps (40% overall) from o-bromoanisole and allylacetylene via the carbene complex 12 and naphthol complex 13.7J8 Reaction of 2-lithio-2-propyl-l,3-dithiane (6a) with 11 in THF-HMPA produced primarily the reduction product 14 (46% isolated yield) along with a product tentatively identified as a coupling product of 2-propyl-1,3-dithiane. Heating a methyl alcohol solution of 11 with the thiazolium salt 15 and triethylamineg again gave the naphthol 14, in 90% yield. The a-alkoxy anion 8 gave a complex mixture of products, with no carbonyl-containing species in significant amount. Reaction of the cyanohydrin acetal anion 7 gave a product from conjugate addition to 11, but it was identified as 16 (43% yield), in which cyanide anion has added. Apparently the cyanide liberated during the usual hydrolysis sequencella on the cyano hydrin acetal was sufficient to produce 16. T h e deliberate addition of cyanide anion (KCN, methyl alcohol a t reflux) followed by treatment with dilute acid to induce elimination of methyl alcohol gave cyanophenol 16 in 74% yield. Methylation of the free phenolic hydroxyl produced the trimethoxy derivative 17 ( 7 5 4 5 % yield overall from 11). Obvious routes lead from 17 to key intermediate 5a, but none have been sufficiently successful to give a practical pathway. For example, addition of n-propyllithium (ether, 25 "C) gave a product (49% yield) from substitution for a methoxy group, tentatively identified as 18.19 Similar results were obtained (77% yield of 18) with n-propylmagnesium bromide. Hydride reduction was also unsatisfactory. T h e cyano group was resistant to reduction (with diisobutylaluminum hydride, L-Selectride, and lithium triethylborohydride; days a t 25 "C); lithium aluminum hydride produced the desired aldehyde but in only 16% yield and again accompanied by a product where one methoxyl was replaced by hydride
(14%). In our studies, the only other successful conjugate additions to 11 by a carbon nucleophile involved the lithium and potassium salts of nitromethane and the potassium salt of nitroethane. Both soluble lithionitromethane and the insoluble potassium analogue added to 11 in THFHMPA a t 23 "C to give a stereoisomeric mixture of adducts 19 in 95% yield. Loss of methyl alcohol proceeded smoothly upon addition of 2-3 mol equiv of magnesium (18)(a) For the detailed procedure of the preparation of 1 1 and of 3, see: Semmelhack, M. F.; Bozell, J. J.; Keller, L.; Sato, T.; Spiess, E. J.; Wulff, W.; Zask, A. Tetrahedron, in press. (b) For a review of the alkyne cycloaddition with carbene-chromium complexes, see: Dotz, K. H. Pure Appl. Chem. 1983,55,1689. (19)For related nucleophilic substitution by an organolithium reagent for an aryl methoxyl group adjacent to an electron-withdrawing group, see: Meyen, A. I.; Cabel, R.; Mihelich, E. D. J . Org.Chem. 1978,43,1372.
5568 6. O r g , Chem , Vol. 50, N o . 26, 1985
d
Semmelhack et al.
G g R M&!,yrH TALR
Me?
No?
'.=5J+
G & A \ ,
a
d
Meb
4)
Me0
19 R = U
20 R : H
21R H
22 R - Me
23 R : M e
2bR:Me
,A,
bromide etherate. T h e easily oxidized naphthol was converted to the methyl ether 20 only with difficulty, the optimum procedure involving a mixture of methyl iodide and potassium carbonate in acetone (40% yield). Unfortunately Nef-type reaction of the nitromethyl unit to give an aldehyde 21 was not successful using a variety of old and new procedures.20 The corresponding intermediates from nitroethane (22, 23) were obtained in better yields but also could not be converted to the acetyl derivative 24 in useful efficiency. With the general failure of the intermediates from direct addition to 11 and a n expectation that the substituent at C-2 (allyl) was a t least partly responsible for hindering 1,6addition, we considered conjugate addition and enolate trapping with carbon electrophiles starting from the simpier quinone ketals 9 and 10. T h e use of H M P A , tetramethylethylenediamine, or Dabco in reaction of n-butyllithium with 9 and 10 was not promising although reductive cleavage of a ketal oxygen was much less prevelant. T h e primary competing pathway is 1,2-addition. For example, addition of 10b to a solution of n-butyllithium in T H F containing 2 mol equiv of HMPA gave a mixture of about equal amounts of 1,2- and 1,4-addition Reaction of 2-lithio-2-propyl-l,3-dithiane (6a) with 44 in T H F containing 2 mol equiv of HMPA was much more selective; protonation of the intermediate gave the 1,4addition product 25 in 86% yield while quenching with
25 R:H 26 R - a l l y l
b. R z nBu c . R : Me
R
J-&
Q bH
29 a : R - H b: RzC-nBu
6
or quinone ketal examples have been reported nor any attempt to trap the presumed enolate anion intermediate with electrophiles other than protons. The acylate-nickel complex 27a from n-propyllithium reacted with 11 (-50 "C, 1.5 h) to give only the product from reductive cleavage, 14 (67% yield). However, reaction of 27a with the unsubstituted quinone ketal 10a (-50 "C) followed by protonation gave the acylated product 28 in 91% yield. The efficiency and simplicity of this direct nucleophilic acylation led us to study the process in related systems. A limited survey was carried out on reactions of the acylate-nickel complex 27b from n-butyllithium, with 9 and 10 as substrates, and final quenching with aqueous ammonium chloride. Addition of 27b to benzoquinone dimethyl monoketal (9a) led t o a fast reaction a t -50 "C and produced the reductive-cleavage product (hydroquinone monomethyl ether) in 94% yield. T h e ethylene ketal analogue 9b was equally unsuccessful, giving a mixture of ketal cleavage products 29a and 29b. In the naphthalene series, reductive cleavage is much less favorable; the dimethyl ketal 10a gives only 1,Caddition (30, 91%) while the ethylene ketal 10b a t -50 "C gives both addition (31, 67%) and cleavage (32, 12% yield; identified tentatively by spectroscopic data on the diacetate). At -78 "C, the yield from 10b is a bit higher but the ratio is the same (83:17). Trapping experiments with carbon electrophiles involved the intermediate enolate 33 (not isolated) from addition of anion 27b to quinone ketal loa. Acylate anion 27b was prepared a t -50 "C in T H F (10-fold molar excess) and a solution of 10a was slowly added a t -50 "C. After the mixture had been stirred a t -78 "C for a few minutes allyl iodide (50 mol equiv) and HMPA (50 mol equiv) were added. The mixture was warmed slowly to 21 "C, and adduct 34 was isolated in 85% yield (single r
b
7
35:R=Me 37:R= nPr
28
R
@YQ$
0,
32 AH
38a: R-H b: R:Pr
Pr
39
40
30: R-Me 31: R--R:
cnrcn,
excess allyl bromide produced the fully assembled intermediate 26 in 60% yield. Parallel with this success, a still more efficient process was worked out based on acylatenickel complexes as carbonyl anion equivalents. The acylate-nickel complexes 27 are prepared from an organolithium reagent and nickel tetracarbonyl a t low temperature but are not easily isolated and are easily decomposed by heat (25 "C) and oxygen.6 Reaction with simple enones is selective for 1,4-addition; proton quench gives a 1,4-diketone product.6 Cyclic enones give only moderat,e yields in the few reported examples; no quinone
isomer; assigned as trans on the basis of related alkylations of cyclohexanone enolatesZ2). An identical reaction but using methyl iodide produced the parallel product 35 in 43% yield, but it was accompanied by a second product (22Y0 yield) tentatively assigned structure 36 on the basis of spectral data. A similar reaction with n-propyl iodide as the trapping agent was still more complicated. In addition to the expected adduct (37; 21% yield) and the simple adduct from proton quenching (30; 22%), products
(20) (a) Olah. G.; Arbananghi, M.; Vankar, Y. D. Synthesis 1980,662. (b) Kornhium, N.; Brown. R. A. J; ,4771. ('hem. Sor. 1965, 87, 1742. C?l) ITnprihlished work of Dr. I . Sat(.. Princeton IT!iiversity. 1982.
(22) For a parallel example, from dialkylcuprate addition to 2inethylcyclohexenone and trapping of the enolate, see: Boeckman, R. K. ./ Org. Chem. 1973, 38, 4450.
41
42
43
J. Org. Chem., Vol. 50, No. 26, 1985 5569
Addition of Acylate-Nickel Complexes (38a, 10% tentatively identified by 'H NMR spectral analysis; 39, 8 % ) from 0-alkylation of the enolate appeared, as well as t h e product from dialkylation (38b; 34%). Clearly, with relatively slow alkylation, additional processes can become important including proton transfer to generate the enolate anion of 37. With n-propyl bromide, the only products were 39 (75%) and 40 (13%), from methyl alcohol elimination and 0-alkylation of the phenol. Quenching of the intermediate enolate 33 with carbonyl group electrophiles was also only partially successful. For example, reaction with acetaldehyde gave two major adducts 41 (40%) and 42 (31%), in addition to the product (30,7%) from simple protonation. Both adducts obviously derive from the expected first product 43, suggesting an efficient trapping procedure. Unfortunately, both acetyl chloride and ethyl acetate gave exclusively the product (30) from simple proton transfer. N a n a o m y c i n A (2) and Deoxyfrenolicin (3). ( a ) F o r m a l S y n t h e s i s of N a n a o m y c i n A (2). As before, reaction of methyllithium with nickel tetracarbonyl at -50 "C in ether gave acylate anion 27c. Addition of quinone ketal 4423followed by excess allyl iodide (HMPA added)
of acylate anion 27a t o 44, with trapping by allyl iodide. T h e diketo ketal 50 was converted t o keto hydroquinone 51 by acid hydrolysis under argon (97% yield), and sodium borohydride reduction produced the triol 52 (98% yield). Oxidation of the hydroquinone with DDQ gave the key intermediate 53 (45%) and palladium-promoted cyclization as before gave the pyrano ester 54 (3:l trans:cis, 70%). In the presence of BBr, a t 0 "C, the cis/trans mixture was converted nearly quantitatively t o the trans isomer; the phenol ether was cleaved,5b and finally the methyl ester was hydrolyzed t o produce (f)-deoxyfrenolicin (3).5b S u m m a r y . T h e conjugate addition of acylate-nickel complexes t o 2,3-unsubstituted naphthoquinone monoketals is particularly efficient. Benzoquinone monoketals and a 3-substituted naphthoquinone monoketal are not effective substrates due to preferential reductive cleavage of a ketal alkoxy group, presumably via electron transfer. Successful conjugate addition produces an enolate anion which can be trapped with allyl iodide, methyl iodide, and acetaldehyde. Simple alkyl halides, esters, and acyl halides are not efficient trapping agents. Combined with the palladium-promoted alkoxy carbonylation procedure for pyran ring synthesis, the acylatenickel conjugate addition reaction provides a particularly simple approach t o the isochroman naphthoquinone antibiotics. Experimental Section
46: R = Me 51: R = Pr
45: R = Me 50: R = Pr
* M
00 OH 41: R = Me 52: R = Pr
48: R = Me 53: R = Pr
Mw
49a: t r a n s , R - M e b: cis, R: Me
54a: trans, R - P r b:cis, R - Pr
02Me
led t o the adduct 45 which was isolated by flash chromatography, 54% yield, m p 126-127 "C. T h e ketal unit was hydrolyzed under argon with a mixture of 6 M hydrochloric acid and dioxane, to produce the hydroquinone 46 (100%). The ketone unit was reduced with sodium borohydride t o give t h e triol 47, m p 139.5-142 "C, in 95% yield. T h e n reoxidation with DDQ (0 OC, 1 h) lead t o the key intermediate 48,66% yield after chromatographic purification. Treatment of 48 with 0.1 mol equiv of palladium dichloride, excess cupric chloride, and carbon monoxide a t 1.1atm in methyl alcohol led directly t o the pyran ester isomer 49a and 49b in the ratio 3:2, 66% yield together. Recrystallization gave a pure sample of the major isomer (trans), with m p 144.5-145 "C. Previous had demonstrated the equilibration of 49a and 49b and the deprotection of the phenol and carboxylic acid to produce (+)-nanaomycin A (2). (b) Deoxyfrenolicin (3). In a parallel set of experiments, adduct 50 was prepared in 82% yield from addition (23) Wheeler, D. M. S.; Crouse, D. J. J . Org. Chem. 1981, 46, 1814.
Spectra. Proton nuclear magnetic resonance ('H NMR) spectra were recorded with a Perkin-Elmer R 24B spectrometer operating at 60 MHz or a JEOL FX-90Q Fourier transform spectrometer operating at 90 MHz. Peak positions are reported in parts per million relative to tetramethyhilane internal standard. Carbon nuclear magnetic resonance (13C NMR) spectra were recorded with a JEOL FX-9OQ Fourier transform spectrometer operating at 22.5 MHz. Peak positions are reported in parts per million relative to deuteriochloroform (6 77.00). Spectra which were recorded with off-resonance decoupling have peaks reported as singlet (s), doublet (d), triplet (t), or quartet (q). Infrared (IR) spectra were recorded on a Perkin-Elmer Model 299 spectrometer. Peak intensities were recorded as strong (s), medium (m),or weak (w). The 1606-cm-' signal of polystyrene was used for calibration. Mass spectra were recorded on an AEI MS-902 instrument or a Hewlett-Packard 5487 GC-MS with electron-impactionization. Chromatography. Medium-pressureliquid chromatography (MPLC) was done by using Lobar prepacked silica gel columns at pressures up to 50 psi applied by a Fluid Metering Inc. Model RP lab pump. UV-active fractions were detected with an ISCO Model UA-5 Absorbance monitor. Column chromatography was done with E. Merck silica gel 60 (0.0404.063mm). Analytical thin-layer chromatography (TLC) was done with E. Merck Reagents silica gel 60 F-254 aluminum-backed plates with a 0.2-mm thickness. Developed plates were visualized under UV light and by charring with 25% aqueous sulfuric acid. Reagents and Solvents. Diethyl ether (ether), tetrahydrofuran (THF), and p-dioxane were distilled under argon from benzophenone ketyl immediately before use. Benzene, chlorotrimethylsilane, dimethylformamide,hexamethylphosphoramide (HMPA),and diisopropylaminewere distilled from calcium hydride (under reduced pressure as necessary) and stored under argon. tert-Butyl alcohol was distilled from calcium oxide, under argon. Dichloromethane was distilled from phosphorus pentoxide, under argon. Methanol was distilled from magnetsium under argon. Commercial cuprous iodide (Alfa) was further purified according to a literature procedure.24 Anhydrous cupric chloride was heated at 100 "C under vacuum (0.01 mm) for 15 h and then stored under argon. Triethylamine was filtered through a short plug of alumina immediately before use. n-Butyllithium and methyllithium were used as solutions in hexane and their concentrations were determined by using a literature procedure.25 (24) Kauffman, G. B.; Teter, L. A. Inorg. Synth. 1963, 7, 9. (25) Kofron, W. G.; Baclawski, L. M. J. Org. Chem. 1976, 41, 1879.
5570 J . Org. Chem., Vol. 50, No. 26, 1985
Semmelhack et al.
which was chromatographed on silica gel with a mixture of ethGeneral Information. The term "concentration" refers to er/dichloromethane/hexaneas eluent. The major band (R, 0.34 removal of solvent at water aspirator pressure with a Buchi Rowith 1:l:l solvent mixture) was collected to give 85 mg (74%) of tovapor-R. The term "under argon" implies that the apparatus 16 as a tan amorphous solid. 'H NMR (CDCl,) 6 3.73 (br, d, 2 was evacuated (aspirator or oil pump) and then filled with argon H, J = 5.9 Hz), 3.98 (s, 3 H), 4.01 (s, 3 H), 5.0-6.2 (m, 3 H),5.95 3 times. Melting points and boiling points were uncorrected. (br s, 1 H), 6.91 (br d, 1H, J = 8.4 Hz), 7.49 (t, 1H, J = 8.4 Hz), Elemental analyses were carried out by Scandinavian Microan7.79 (br d, 1 H, J = 8.4 Hz); IR (CHCl,) 3100-3600 (m), 2935 (m), alytical Labs, Herlev, Denmark. Lithium diisopropylamide 2230 (m), 1655 (m), 1580 (s), 1390 (s), 1290 (s), 1265 (s), 1070 (s), prepared by treating a solution of the amine (1.1mol equiv) in 1027 (s) cm-'; mass spectral mol wt 257. THF or ether at -78 "C, under argon, with n-butyllithium (1.0 Preparation of 2-Allyl-3-cyano-1,4,5-trimethoxymol equiv). The solution was warmed to 0 "C for 15 min and then naphthalene (17). To a solution of 392 mg of 16 (1.46 mmol) cooled to -78 "C. in 3 mL of THF was added 60 mg of sodium hydride (2.5 mmol) Reaction of 2-Lithio-2-n-propyl-1,3-dithiane (sa) with and 680 mg of dimethyl sulfate (5.4 mmol). After it was stirred 1,1,5-Trimethoxy-2-allyl-4-oxo-1,4-dihydronaphthalene( 1 1). for 30 min, the reaction mixture was diluted with there, washed A solution of the carbanion was prepared by addition of 0.20 mmol with water, and stirred with saturated aqueous sodium carbonate of 2-n-propyl-1,3-dithiane in 0.5 mL of THF at -78 "C followed for 1 h before being dried over potassium carbonate. Chromaby warming to -20 "C for 1haloHexamethylphosphoramide (0.36 tography (silica; 1:1:4 mixture of ether/dichloromethane/hexane mmol) was added to the solution at -78 "C, and, after the mixture as eluent) gave 381 mg (92%) of a colorless solid (mp 95-96.5 "C, became homogeneous, a solution of 50 mg (0.18 mmol) of 11 in R, 0.26) which was identified as 17 on the basis of the following 0.3 mL of THF was added. After 10 min, the reaction mixure spectral data: 'H NMR (CDC13)6 3.70 (br d, 2 H, J = 6.2 Hz), was quenched with aqueous ammonium chloride and allowed to 3.88 (s, 3 H), 4.01 (s, 3 H), 4.02 (s, 3 H), 4.9-6.3 (m, 3 H), 6.93 warm to 25 "C. The organic layer was washed sequentially with (dd, 1 H,J = 1.7, 7.2 Hz), 7.4-7.8 (m, 2 H); 13CNMR (CDCl,) 1%aqueous sulfuric acid, water, and saturated aqueous sodium 6 32.5,56.2,58.4, 62.2,63.2, 105.5, 106.9, 114.8, 115.7,116.5, 119.4, chloride before drying (MgSO,). Analytical TLC indicated that 128.9, 129.7, 133.5, 134.9, 150.1,156.7, 158.8; IR (CHC13) 2925 (w), starting material was gone and that two products had formed. 2225 (w), 1613 (w), 1572 (m), 1370 (s), 1267 (m), 1065 (s), 1040 These were separated by preparative TLC with a 1:1:4 mixture ( 8 ) cm-'; mass spectrum, m / e 283 (M', loo), 268 (37), 253 (14), of ether, dichloromethane, and hexane as eluent. The first product 237 (18), 236 (17), 225 (12), 193 (8), 167 (19), 149 (37). to be eluted (14 mg, R, 0.32) showed no aryl proton signals in the Reaction of 17 with n -Propyllithium. A solution of 41 mg 'H NMR spectrum, and appears to be a byproduct derived from (0.145 mmol) of 17 in 3 mL of ether was treated with 0.146 mmol n-propyl-1,3-dithiane. The second component (20 mg, 46% yield, of n-propyl lithiumz6(0.87 mL of a 0.15 M solution in ether) at R, 0.20) was identified as naphthol 14: 'H NMR (CDCl,) b 2.50 25 "C. Analytical TLC indicated the immediate disappearance (br d, 2 H), 3.87 (s, 3 H), 3.92 (s, 3 H), 4.9-5.4 (m, 2 H), 5.7-6.2 of starting material and the formation of one major product. The (m, 1 H), 6.55 (s, 1 H), 6.75 (d, 1 H, J = 8.0 Hz), 7.27 (t, 1 H, J reaction mixture was hydrolyzed with 15% aqueous hydrochloric = 8.0 Hz), 7.60 (d, 1H, J = 8.0 Hz); NMR (CDC13)35.4, 56.4, acid, washed sequentially with water and saturated aqueous so57.6, 106.3, 110.2, 114.2, 116.6, 117.5, 119.1, 125.9, 125.5, 135.9, dium chloride, and dried (MgSO,). Concentration gave a residue 143.3,150.8,156.4; IR (CHCl,) 3520 (w),2930 (w), 1623 (w), 1598 which was chromatographed (silica gel; 1:1:4 mixture of ether/ (s), 1582 (s), 1380 (s), 1275 (s), 1060 (s) cm-'; mass spectrum, m / e dichloromethane/hexane as eluent). Collection of the band at 244 (M', loo), 229 (12), 188 (9), 187 (81,135 (9), 128 (9), 115 (11). R, 0.32 gave 21 mg (49%) of an oil which was identified as 2Attempted Conjugate Acylation of 11 Using Stetter's allyl-3-cyano-1,5-dimethoxy-4-n-propylnaphthalene (18) on the Reaction with Thiazolium Salt 15. A solution of 14.4 mg (0.053 basis of the following spectral data: 'H NMR (CDCl,) 6 0.7-1.9 mmol) of naphthoquinone monoketal 11, n-butyraldehyde (0.050 (m, 5 H), 3.53 (t, 2 H), 3.76 (d, 2 H), 3.88 (s, 3 H),3.98 (s, 3 H), mL), triethylamine (0.020 mL), and thiazolium salt 15 (4.0 mg) 4.9-6.3 (m, 3 H), 6.94 (d, 1 H), 7.53 (t, 1 H), 7.74 (d, 1 H); IR in methyl alcohol (1.0 ml) was prepared under argon by careful (CHCl,) 2950 (m), 2210 (w), 1610 (w), 1560 (m), 1455 (m), 1370 freeze-pump-thaw cycles. The mixture was heated in a sealed (s), 1260 (s), 1060 (s) cm-'; mass spectrum, m / e 295 (M'), 85.7, tube a t 100 "C for 6 days. Analytical TLC indicated complete 280 (6), 267 (64), 251 (100);mass spectral mol wt calcd for C19conversion of 11 and one predominant product (ether on silica HzlOzNm / e 295.1572, found 295.1570. The same reaction was gel; R, 0.47). The solution was diluted to 25 mL with ether and carried out with n-propylmagnesium bromide (THF, 55 "C, 0.5 washed sequentially with 1N sulfuric acid, water, and brine. The h). The reaction was quenched with saturated aqueous ammoether solution was dried (MgSO,) and concentrated to give 16.6 nium chloride and dried over potassium carbonate. The major mg of an amber oil. Chromatography on 0.5 g of silica gel provided product was again 18 (77% yield). pure dimethoxynaphthol 14 ('H NMR, IR, TLC; 90% yield). Conjugate Addition of Lithionitromethane to QuinoneAttempted Conjugate Addition of Cyanohydrin Acetal Ketal 11. A solution of nitromethane (0.030 mL, 0.55 mmol) in Anion 7 with NaphthoquinoneMonoketal 11. The ethoxyethyl 1mL of THF was prepared under argon and treated, with stirring, ether of the cyanohydrin of butyraldehyde (32 mg, 0.189 mmol)"* with 0.17 mL (0.36 mmol) of a solution of n-butyllithium (2.1 M) was added to a solution of lithium diisopropylamide at 25 "C and in hexane. The resulting white gel was diluted with 2 mL of stirred for 0.5 h. The resulting solution of 7 was added to a HMPA to give a colorless solution, which was treated with a at -78 "C. The solution of 11 (47 mg, 0.172 mmol) in ether (2 d) solution of 49.0 (0.18 mmol) of naphthoquinone 11 in 2 mL of mixture was warmed to 25 "C and a second equivalent of 7 was THF. The opaque, red-black reaction mixture was stirred at 25 added, because analytical TLC indicated no reaction. Upon "C for 3 h until complete conversion was indicated by analytical addition of HMPA (0.8 mL), the mixture became dark and reTLC. [Et,O; R, product -0.49 (elongated spot, two isomers).] action was complete after 1 h at 25 "C. The mixture was conThe reaction mixture was acidified with 0.03 mL of glacial acetic centrated and then stirred in THF with 6 M aqueous HCl at 25 acid, swirled for a few minutes, and then partitioned between 50 O C for 1 h. The solution was diluted with ether and shaken with mL of ether and 10 mL of half-saturated aqueous lithium chloride. 15% aqueous sodium hydroxide for 5 min. The ether solution The organic layer was washed successively with 3-mL portions was washed with brine, dried (MgS04),and concentrated to leave of saturated aqueous lithium chloride (3X), water (3X),and brine. a residue which was purified by preparative TLC (silica gel, eluting Drying (MgS04),filtration, and concentration gave an amber oil with 1:1:1 ether/dichloromethane/hexane) to provide the cyanide (70 mg) which was dissolved in benzene and filtered through 500 addition product 16 (20 mg, 43%). The compound was prepared mg of silica. Elution with 7:5 petroleum ether/ether gave adduct more efficiently by direct reaction with KCN and is fully char19 as a pale yellow oil, about a 3:2 mixture of isomers by NMR acterized below. Preparation of 2-Allyl-3-cyano-l-hydroxy-4,5-dimethoxy- spectral analysis (signals for -0Me at 6 2.89, 2.85). This sample was used directly below. 'H NMR (CDC13) 6 7.8-7.6 (m, 1 H), naphthalene (16). A solution of 117 mg (0.427 mmol) of 11 and 7.41 (br, t, 1 H, J = 8.0 Hz), 7.2-7.0 (m, 1 H),6.1-5.5 (m, 1 H), 34 mg (0.513 mmol) of potassium cyanide in 2 mL of methanol 5.2-4.95 (m, 2 H),4.8-3.9 (m, 2 H),2.89 and 2.85 (twos, 3 H total, was heated at reflux under argon for 24 h. After it was diluted with ether, the reaction mixture was washed sequentially with 1%aqueous sulfuric acid and saturated aqueous sodium chloride (26) Jones, R. G.; Gilman, H. Org. React. 1959, 6, 352 before drying. Concentration by rotary evaporation gave a residue
Addition of Acylate-Nickel Complexes OCH3),3.8-2.7 (m) overlapping 3.40 (s), 3.31 (s), 3.27 (s), 3.17 ( 8 ) (total area 3.8-2.7 is 9 H), 2.2-1.9 (m, 1 H); IR (neat), 3090 (w), 2960 (m), 2855 (m), 1695 (s), 1645 (w), 1596 (91,1555 (vs), 1475 (s),1445 (m), 1280 (vs) cm;'; mass spectral mol wt 335. Note that the isomeric composition of the product varied from run to run and varied with the counterion. Careful analytical TLC showed marginal separation of the isomers ( A l l , 0.05), and in one run a small amount of each was obtained pure by flash chromatography. Infrared and mass spectral data of the pure isomers were identical with each other and with those of the mixture. Conversion of Nitro Ketal 19 iato t-Allyl-3-(nitromethyl)-l,4,5-trimethoxynaphthalene(20)s (a) Preparation of 2-Allyl-3-(nitromethyl)-l-hydroxy-4,5-dimethoxynaphthalene. A side-armed flask fitted with an oven-dried condenser and a stir bar was charged with 16 mg of magnesium powder (0.66 mmol) and 109 mg (0.30 "01) of mercuric bromide under argon. A mixture of benzene (1mL) and ether (3 mL) was added, the vessel was stoppered, and the suspension was heate'd at 45 "C for 1h. In a separate vessel, a solution of 19.1 mg (0.057 mmol) of nitro ketal 19 in benzene (1 mL) was prepared under argon. The solution of magnesium bromide etherate was allowed to cool and settle, and the supernatant liquid was withdrawn via syringe and added rapidly to the stirred solution of the nitro ketal 19. After addition, the pale amber reaction mixture was stirred for 2.5 h. Analytical TLC of the reaction mixture was ambiguous as the product was later shown to have the same R, as the slower reacting of the nitro ketal isomers. Following the reaction period, the solution was diluted to a volume of 30 mL with ether and washed with two 3-mL portions of water and one 3-mL portion of brine. Drying (MgS04),filtration, and concentration of the solution provided the naphthol as an amber, partially crystalline oil (15.0 mg, 87% yield). The product contained traces of solvent and starting material and was used directly owing to ita oxidative lability. (b) Methylation To Give 20. A round-bottomed flask charged with the crude naphthol and potassium carbonate (15 mg, 0.11 mmol) under argon was fitted with a reflux condenser and a stir bar. A solution of methyl iodide (0.10 mL) in 2 mL of degassed acetone was introduced and the resulting pale yellow reaction mixture was heated under argon at 50 "C for 1 day. A second portion of methyl iodide (0.10 mL) was introduced and heating was continued for an additional 1 day. Analytical TLC (2:l petroleum ether-ether) showed partial conversion of the naphthol (R, 0.33) to the trimethoxynaphthalene 20 ( R f0.42). On other runs, it was found that neither higher temperatures nor longer reaction times improved the yield of 20. The reaction mixture was acidified with 10 drops of glacial acetic acid, then diluted to 40 mL with ether, and washed with brine (3X). Drying (MgSO,), filtration, and concentration gave the crude product (10 mg) as an amber oil that was directly chromatographed on 500 mg of silica gel. Elution with 2:l petroleum ether-ether separated 7.3 mg (36%) of product 20 from 3.5 mg (18%) of starting naphthol. 20: 'H NMR (CCl,) 6 7.68 (d, 1 H, J = 8.5 Hz), 7.40 (t, 1 H, J = 8.5 Hz), 6.84 (d, 1 H, J = 8.5 Hz), 6.2-5.75 (m, 1 H), 5.69 (s, 2 H), 5.1-4.8 (m, CH=CH2, 2 H), 4.01 (s, 3 H), 3.89 (s, 3 H), 3.81 (s, 3 H), 3.63 (dt, 2 H, J = 5.5, 1.0 Hz, CH2CH=); IR (neat) 3080 (w), 3010 (w), 2945 (m), 3850 (m), 1640 (w), 1620 (w), 1595 (m), 1580 (4, 1555 (vs), 1380 (vs), 1345 (s), 1210 (s), 1065 (s) cm-I; mass spectral mol wt 317. Conjugate Addition of 1-Potassio-1-nitroethaneto Quinone Ketal l l . The reaction vessel was charged with a stir bar and potassium hydride (253 mg of a 24.9% dispersion in oil, 1.6 mmol) under argon. The hydride was washed with dry pentane (2 mL), then suspended in HMPA (2 mL), and treated with nitrobenzene (0.13 mL, 1.8 mmol). The mixture was stirred until gas evolution ceased (ca. 5 min) and the formation of the white precipitate of I-potassio-1-nitroethanewas complete. A solution of naphthoquinone monoketal 11 (91 mg, 0.33 mmol) in 0.5 mL of THF and 1 mL of HMPA was added to give an orange-red suspension and then stirred at 23 "C for 5 days. The reaction mixture was treated with about 0.15 mL of acetic acid, stirred at 15 "C for 5 min, and partitioned between 10 mL of half-saturated aqueous lithium chloride and 75 d of ether. The aqueous layer was further extracted with 10 mL of ether and the combined organic layers were washed successively with 6-mL portions of saturated aqueous lithium chloride (4X), water (2X), and brine.
J. Org. Chem., Vol. 50, No. 26, 1985
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The solution was dried (MgSO,), filtered, and concentrated to give a dark brown oil. Flash chromatography on silica gel, 5 g, eluting with 60 mL of 7 5 petroleum ether-ether provided 22 (98.3 mg, 85%), as a pale yellow oil, a mixture of all four diastereoisomers. 'H NMR (CCl,) 6 7.73 (m, 1 H), 7.6-7.33 (m, 1 H), 7.25-7.05 (m, 1H), 6.0-5.4 (m, 1 H), 5.3-4.9 (m, 2 H),4.8-4.2 (m, 1 H), 3.88 (s, 3 H), 3.50-1.80 (series of eight s overlapping other m, total 10 H), 1.40 (br d, 3 H, J = 7.5 Hz); IR (neat) 3080 (w), 2950 (s),2840 (m) 1690 (d, vs), 1640 (w), 1590 (vs), 1555 (vs), 1470 (vs), 1270 (vs), 1060 (s) cm-'; mass spectral mol wt 349. The four adduct isomers were marginally separable by careful TLC (2:l ether-petroleum ether; R, values of 0.45,0.41, 0.37, and 0.34). In one run, the less polar pair was separated from the more polar pair. Mass spectral and IR analysis of the two mixtures were identical with each other and with that of the mixture. Conversion of Quinone Ketal 22 into 2-Allyl-3-(1-nitroethy1)-1,4,5-trimethoxynapht halene (23). (a) Preparation of 2-Allyl-3-(l-nitroethyl)-l-hydroxy-4,5-dimethoxynaphthalene. A solution of dry p-toluenesulfonic acid was prepared by slowly distilling benzenewater azeotrope (5 mL) from a solution of p-toluenesulfonic acid monohydrate (6.2 mg) and benzene (15 mL). After the mixture had been cooled at 25 "C, a solution of 22 (98.3 mg) in 5 mL of dry benzene was introduced and 6 mL of benzene was slowly distilled over 15min, The yellow mixture was cooled, treated with a few drops of saturated aqueous sodium bicarbonate, and then diluted to 40 mL with degassed ether. The solution was washed twice with 5-mL portions of degassed brine, dried (MgS04),filtered, and concentrated. The amber oil obtained was used directly. (b) Methylation To Give 23. Exactly as above for 19, the crude naphthol was converted nearly completely to 23. Flash chromatography of 5 g of silica gel (3:2 petroleum ether-ether) gave a yellow viscous oil, 68.6 mg (75% from 22). 'H NMR (CCl,) 6 7.61 (dd, 1H, J = 7.1, 1Hz), 7.30 (t, 1H, J = 8.0 Hz), 6.75 (dd, 1 H, J = 7.1, 1 Hz), 6.2-5.8 (m, 1 H), 5.53 (4, 1 H, J = 6.5 Hz), 5.2-4.0 (m, 2 H, CH=CH2), 3.94 and 3.84 (two s, 3 H together), 3.60 (s) overlapping 3.7 (m) with area 5 H total, 1.89 (d, 3 H, J = 6.5 Hz); IR (neat) 3090 (w), 2950 (s), 2850 (m), 1645 (w), 1620 (m), 1595 (m), 1580 (vs), 1505 (w), 1460 (s), 1380 (vs), 1070 (vs) cm-'; mass spectra mol wt 331.1419, calcd 331.1419. Reaction of Spiro[ 1,3-dioxolane-2,1'-8'-methoxy-4'(1'iY)naphthalenone)] (44) with 2-Lithio-2-n-propyl-1,3-dithiane (6a) (Proton Quench). n-Butyllithium (0.170 mL of a 2.36 M solution in hexane, 0.40 mmol) was added dropwise under argon at -20 "C to a solution of 2-n-propyl-1,3-dithianeZ7 (65 mg, 0.40 mmol) in 5 mL of dry THF. After it was stirred at -20 "C for 1h, the reaction mixture was cooled to -78 "C; HMPA (143 mg, 0.139 mL, 0.80 mmol) was added followed by a solution of monoketal 44 (80 mg, 0.37 mmol) in 2 mL of dry THF. After the mixture was stirred at -78 "C for 5 min, aqueous ammonium chloride solution 2 mL) was added, and the reaction mixture was warmed to 23 "C. The reaction mixture was diluted with ether, washed once with water and once with saturated brine, dried (MgSO,), and concentrated to afford 138 mg of an oil. Preparative TLC (2:3 ether/hexane) gave 40 mg (86%) of spiro[l,3-dioxolane-2,1'-(8'-methoxy-2'- [2-(2-n-propyl-1,3-dithianyl)1-2',3'dihydro4(l'H)-naphthalenone)J (25);R f 0.3; 'HNMR (CDC13) 6 0.99 (t, 3 H, J = 7 Hz, CH2CH2CH3),1.30-2.97 (m, 13 H, (CH&CH3, S(CH2)~S, O=CCHzCH), 3.89 (s, 3 H, OCH3),4.20 (s, 4 H, OCH2CH20),7.03-7.62 (m, 3 H, Ar); IR (CHC13)2960,2900, 1680 (s, C=O), 1590 (m), 1581 (m), 1470 (m), 1294 (s), 1270 (s) cm-'; mass spectral mol wt 394. Spiro[ 1,3-dioxolane-2,1'-(8'-methoxy-3'-allyl-2'-2-(2-n propyl-1,3-dithianyl)]-2',3'-dihydro-4'( 1'H)-naphthalenone)] (26). n-Butyllithium (0.137 mL of a 2.56 M solution in hexane, 0.35 mmol) was added dropwise under argon at -25 OC to a solution of 2-n-propyl-1,3-dithiane (60 mg, 0.37 mmol) in 5 mL of dry THF. After it was stirred at -25 "C for 5 h, the solution was cooled to -78 "C, HMPA (0.129 mL, 132, mg, 0.74 mmol) was added followed by a solution of monoketal44 (80 mg, 0.34 mmol) in 2 mL of dry THF. After the mixture had been stirred at -78 "C for 5 min, allyl bromide (0.161 mL, 224 mg, 1.85 mmol) was added, and the reaction mixture was allowed to warm to 23 "C. (27) Corey, E. J.; Seebach, D. Angew. Chem., Int. Ed. En& 1075.
1965, 4,
5572 J. Org. Chem., Vol. 50, No. 26, 1985 After 30 min at 23 "C, the mixture was diluted with 100 mL of ether, washed twice with water and once with saturated brine, dried (MgS04), and concentrated to afford 190 mg of crude product. Preparative TLC (1:lether/hexane) gave a major band with Rf 0.40 (89 mg, 60%) of spiro[l,3-dioxolane-2,1'-(8'-methoxy-3'-allyl-2'- [ 2-( 2-n-propyl-l,3-dithianyl)]-2',3'-dihydro-4'(l'H)-naphthalenone)] (26) as a crystalline solid 'H NMR (CDC1,) 6 0.84 (t,3 H, J = 7.5 Hz, (CHz)2CHz)ZCH3), 1.19-2.92 (m, 14 H, (CHZ)ZCH,, S(CHz),S, O d - C H C H , CHZCH=CH,), 3.86 ( ~ ,H, 3 OCHJ, 4.09 (m, 4 H,OCH2CHzO), 4.95-5.14 (m, 2 H, CHzCH=CHZ),5.88 (m, 1 H, CH2CH=CH2), 6.97-7.60 (m, 3 H, Ar); IR (CHCl,) 2945 (m), 1675 (s, C=O), 1580 (s), 1463 (m), 1309 (m), 1259 (vs, C-0). 885 (s, C=C) cm-'; mass spectral mol wt 434. General Procedure for Reaction of Acylate-Nickel Complex 27b with Quinone Monoketals 9 and 11. To 12 mL of dry THF in a 100-mL flask under argon was added all at once nickel tetracarbonylZs (1.30 mL, 10.0 mmol) at -50 "C. With vigorous stirring, n-butyllithium (5.10 mL of a 2.0 M solution in n-hexane, 10.0 mmol) was added over 10 min. The mixture was stirred for 1.5 h at -50 "C to give a dark red-brown solution. Naphthoquinone monoketal(9a, 9b, loa, or lob; typically 1.00 mmol) was added dropwise with a syringe pump over 4.5 h. The mixture was stirred for 4.5 h at -50 "C and then cooled to -78 "C. HMPA (9 mL, 51.7 mmol) was added all at once into the mixture followed by the quenching agent (excess 10% aqueous ammonium chloride, methyl iodide, allyl iodide, n-propyl iodide, n-propyl bromide; typically 50 mmol of the halides). After addition, the mixture was allowed to warm gradually to 25 "C and then stirred for 15 h. The excess nickel carbonyl was decomposed by careful addition of iodine in ether until the brown iodine color persisted. The mixture was partitioned between ether and aqueous ammonium chloride,and the ether layer was washed with saturated sodium chloride solution containing sodium sulfite until it was colorless, then dried (MgSO,), filtered, and concentrated to leave an orange liquid. The moderately volatile components (HMPA and byproducts derived from excess acylate nickel complex) were removed by short-path distillation (66-70 "C air bath, 0.004 mmHg), and the residual oil was chromatographed on silica gel (15 g; eluent was n-hexanelbenzene) to afford the addition product or reduction product. (a) With 9a and proton quench, the only product detected was hydroquinone monomethyl ether, 113 mg, 94% yield. (b) With 9b and proton quench (0.66-mmol scale), chromatography gave the products of reductive cleavage, 29b (61 mg, 40%) and 29a (44 mg, 43%). 29a: 'H NMR (acetone-d,) 6 3.90 (m, 4 H), 6.76 (s, 4 H); IR (Nujol) 3460, 3250, 1603, 1500, 1220, 1037,830 cm-'; mass spectral mol wt 154.0629,calcd for C8H1003 154.0631;mp 93-95 "C (CC1.J. 29b: colorless oil; 'H NMR (CDC1,) 6 0.91 (br t, 3 H, J = 7.0 Hz), 1.1-1.8 (m, 4 H),2.36 (t, 2 H, J = 7.2 Hz),4.12 (m, 2 H,AA'BB'), 4.40 (m, 2 H,AA'BB?, 6.80 (s, 4 H);13CNMR (CDC1,) 6 13.6, 22.2, 26.9, 33.9, 62.8, 66.9, 116.1, 150.2, 152.6, 174.0; IR (neat) 3400, 1730, 1520 cm-'; mass spectral mol w t 238.1209, calcd for C13H1804 238.1206. (c) With 10a (0.88 mmol) and proton quench, chromatography produced 232 mg (91%) of 30 as a colorless semisolid. 'H NMR 2.44 (m, (CDC1,) 6 0.80 (br t, 3 H, J = 7.0 Hz), 0.9-1.6 (m, 4 H), 2 H), 2.80 (dd, 1 H, J = 18.0, 2.9 Hz), 2.92 (s, 3 H), 3.04 (dd, 1 H, J = 18.0, 5.4 Hz), 3.83 (dd, 1 H,J = 5.4, 2.9 Hz), 7.38-7.77 (m, 3 H),8.05 (m, 1 H); 13CNMR (CDC13) 6 13.67, 22.01, 25.21, 126.35, 126.78, 129.12,132.2, 37.73,42.11, 48.88,49.48,52.40,98.34, 132.4, 137.8, 195.53, 208.48; IR (neat) 1715, 1700 cm-'; mass spectral mol w t 290.1509, calcd 290.1519. (d) With IOb (0.79 mmol) and proton quench, chromatography produced adduct 31 (colorless oil, 153,mg 67%) and reduction product 32 (19 mg, 12%). Spectral data for 31: 'H NMR (CDC13) 6 0.84 (t, 3 H, J = 7.2 Hz),1.00-1.65 (m, 4 H), 2.28-2.86 (m, 2 H),2.95 (m. 2 H),3.57 (t, 1 H, J = 5.1 Hz), 4.0-4.44 (m,4 H), 7.32-7.70 (m, 1H), 8.02 (m, 1 H); 13CNMR (CDC1,) 6 13.7, 22.1,
(28) Nickel carbonyl is toxic and volatile and does not have a strong odor; therefore, it is well-known as a reagent to be used after obtaining full information on its properties. A useful discussion can be found in a brochure from the Matheson Co., entitled "Nickel Carbonyl is Dangerous"
Semmelhack et al. 25.4, 38.2, 43.9, 54.8, 65.1, 66.1, 106.4, 124.3, 126.6, 129.3, 132.2, 133.5, 140.2, 193.0, 208.5; IR (neat) 1715 (s), 1700 (m) cm-'; mass spectral mol wt 288.1343, calcd for Cl7HZ0O4 288.1363. The reduction product 32 was converted to the diacetate (acetic anhydride/pyridine) for spectral characterization. 'H NMR (CDCl,) 6 2.11 (s, 3 H), 2.44 (s, 3 H), 4.33 (m, 2 H, AA'BB'), 4.60 (m, H, AA'BB?, 6.78 (d, 1 H, J = 7.9 Hz), 7.13 (d, 1 H, J = 7.9 Hz), 7.54 (m, 2 H), 7.80 (m, 1 H), 8.28 (m, 1 H); IR (CHCI,) 1740, 1587, 1370 cm-'; mass spectrum (70 eV, EI), m / e 228 (M', l l % ) , 2.39 (4), 160 (6), 149 (lo), 111 (15), 97 (25), 87 (loo), 85 (28), 83 (291, 71 (41), 70 (24), 69 (35). (e) With 10a (1.03mmol) and quenching with excess allyl iodide, chromatography produced 34 as a colorless oil (288 mg, 85%): 'H NMR (CDC13)6 0.84 (br t, 3 H, J = 7 Hz), 1.0-1.6 (m, 4 H), 2.46 (t, 2 H, J = 7.0 Hz), 2.6-3.0 (m, 3 H), 2.91 (s, 3 H), 3.40 (s, 3 H), 3.74 (d, 1 H, J = 3.6 Hz), 5.0-5.3 (m, 5.3 (m, 2 H), 5.8 (m, 1 H), 7.3-7.8 (m, 3 H), 7.96 (m, 1 H); I3C NMR (CDC1,) 6 13.67, 22.1, 25.4, 36.1,42.2,46.7,49.2, 49.4,55.0,99.0, 117.7, 125.9, 127.2, 129.1,132.4,132.6,136.2,138.9,197.9,208.5; IR (neat) 1713,1695, 1608 cm-'; mass spectral mol wt 330.1817, calcd for CZ0H2@O4 330.1833. (f) With 10a (1.03 mmol) and quenching with excess methyl iodide, chromatography produced 35 (colorless oil, 95 mg, 43%) and 36 (colorlessoil, 55 mg, 22%). Spectral data for 35: 'H NMR (CDCI,) 6 0.86 (br t, 3 H, J = 7 Hz), 1.0-1.7 (m, 4 H), 1.36 (d, 3 H, J = 7.2 Hz), 2.51 (t, 2 H, J = 7.2 Hz), 3.03 (br quintet, 1 H, J = 7 Hz), 3.08 (9, 3 H), 3.32 (s,3 H),3.47 (d, 1 H, J = 6.3 Hz), 7.4-7.7 (m, 3 H), 8.00 (m, 1 H); NMR (CDCl,) 6 13.8, 17.2, 22.2, 25.5, 41.9, 49.5, 50.1, 60.4, 99.0, 126.1, 127.5, 129.2, 132.4, 138.9, 198.8, 208.6; IR (neat) 2960, 1693, 1240, 1047 cm-'; mass spectral mol wt 304.1646, calcd 304.1676. Byproduct 36 showed the following data: 'H NMR (CDCl,) 6 0.96 (t,3 H, J = 7.0 Hz), 1.2-1.9 (m, 4 H), 1.32 (s,3 H), 2.40 (d, 1 H, J = 12.5 Hz), 2.6-2.9 (m, 2 H), 2.74 (d, 1 H, J = 5.4 Hz), 3.00 (s, 3 H), 3.48 (s, 3 H), 3.57 (dd, 1 H, J = 12.5, 5.4 Hz), 7.44 (td, 1 H, J = 7.2, 1.8 Hz), 7.62 (td,1 H, J = 7.0, 1.8 Hz), 7.78 (m, 1 H), 7.97 (m, 1 H); 13C NMR (CDC1,) 6 13.9 (q), 22.5 (t),23.53 (q), 26.0 (t),31.9 (t),35.5 (t),48.6 (d), 49.5 (q), 51.8 (q), 78.84 (s), 97.5 (s), 126.4 (d), 127.6 (d), 129.0 (d),133.1 (d), 140 (s), 197.6 (s), 212.8 (9); IR (neat) 3450, 1712, 1690, 1605 cm-'; mass spectrum (20 eV, EI), m / e 316 (M - 18). Treatment of 36 with p-toluenesulfonic acid in ether at 25 "C for 2 h induced elination of water to give a product tentatively identified as i on the basis of spectral data. 'H NMR OH
I
(CDCl,) 6 0.88 (br t, 3 H, J = 6 Hz), 1.1-1.7 (m, 4 H), 2.30 (s, 3 H), 2.60(t, 1 H, J = 7.2 Hz), 4.01 (9, 3 H), 5.75 (d, 1 H,J = 1.8 Hz), 6.25 (d, 1H, J = 1.8 Hz), 6.65 (s, 1H), 7.40-7.80 (m, 3 H), 8.28 (m, 1 H); IR (CHCI,) 1773, 1704, 1604, 1378 cm-l; mass spectral mol w t 284. (g) With 10a (0.86 mmol) and quenching with n-propyl iodide, chromatography produced 37 (colorless oil, 61 mg, 21.4%),30 (54 mg, 22%), 38a (26 mg, lo%), 38b (22 mg, 8%), and 39 (108 mg, 34%). Data for 37: 'H NMR (CDCl,) 6 0.84 (t, 3 H, J = 7.0 Hz), 0.95 (t, 3 H, J = 7.0 Hz), 1-2 (m, 8 H), 2.42 (t, 2 H, J = 7.2 Hz), 2.78 (m, 1H), 2.94 (s, 3 H), 3.39 (s, 3 H), 3.60 (d, 1H,J = 4.1 Hz), 7.4-7.8 (m, 3 H), 7.98 (m, 1 H); IR (CCl,) 2980, 1710 (sh), 1693cm-'; mass spectral mol wt 332.1958, calcd for 332.1989. Data for 38b: 'H NMR (CDC1,) 6 0.66 (br t, 3 H, J = 7 Hz), 0.96 (br t, 3 H, J = 7.0 Hz), 1.08 (br t, 3 H, J = 7.0 Hz), 1-2.2 (m, 10 H), 2.3-2.7 (m,2 H), 2.85 (s, 3 H), 3.39 (m, 3 HI, 3.60 (m, 1 H,ABC*), 3.68 (9, 1 H),3.82 (m, 1 H, ABC2),7.2-7.6 (m, 3 H), 7.68 (m, 1 H); 13CNMR (CDC13)6 10.64 (q), 13.62 (91, 14.21 (q), 21.20 (t), 21.96 (t),23.42 (t),25.37 (t), 31.06 (t), 37.35 (t),48.88 (q), 49.10 (q), 61.72 (d), 73.80 (t), 98.18 (s), 122.40 (4,122.56 (4, 126.68 (d), 12.89 (d), 128.90 (d), 131.99 (s), 133.67 (s), 148.08 (s), 207.72 (s); mass spectral mol wt 374.2428, found 374.2459. Data for 39: 'H
Addition of Acylate-Nickel Complexes NMR (CDCl,) 6 0.95 (br t, 3 H, J = 7.0 Hz), 1.12 (t, 3 H, J = 7.0 Hz), 1.28-2.05 (m, 6 HI, 3.15 (t, 2 H, J = 7.0 Hz), 3.93 (s, 3 HI, 4.12 (t, 2 H, J = 7.0 Hz), 6.96 (s, 1 H), 7.58 (m, 2 H, AA'BB'), 8.23 (m, 2 H, AA'BB?; IR (CCl,) 2980, 2960, 2900, 1680, 1603, 1373 cm-'; mass spectrum (70 eV) m/e 300 (M', 100%),258 (6.51, 257 (LO), 243 (40),201 (55),186 (16), 173 (7.0), 143 (LO), 115 (8.0). Data for 38a: 'H NMR (CDCI,) 6 0.68 (br t, 3 H, J = 7.0 Hz), 0.8-1915 (m, 8 H), 2.01 (m, 2 H), 2.88 (s, 3 H), 3.38 (9, 3 H), 3.78 (m, 2 H), 3.80 (d, 1 H, J = 7.2 Hz), 4.86 (d, 1 H, J = 7.2 Hz), 7.25-7.80 (m, 4 H). (h) With 10a (0.59 mmol) and quenching with n-propyl bromide, chromatgraph produced 39 (133 mg, 75%) and 40 (20 mg, 13%). Data for 40: 'H NMR (CDCl,) 6 0.96 (br t, 3 H, J = 7.0 Hz),1.2-1.9 (m, 4 H), 3.18 (t, 2 H, J = 7.2 Hz), 3.96 (s, 3 H), 7.19 (s, 1 H), 7.62 (m, 2 H, AA'BB'), 8.20 (m, 2 H, AA'BB?; IR (CClJ 3420,2980, 1665, 1605,1390 cm-'; mass spectral mol wt 258.1243, found 258.1257. (i) With loa (1.00 mmol) quenching with acetaldehyde and chromatography produced 41 (130 mg, 40%) and 42 (105 mg, 31%). Data for 41: 'H NMR (CDCl,) 6 0.66 (br t, 3 H, J = 7.0 Hz), 0.8-1.5 (m, 4 H), 1.10 (t,3 H, J = 7.2 Hz), 1.90 (m, 2 H), 2.30 (m, 2 H), 2.81 (9, 3 H), 3.52 (9, 3 H), 4.55 (d, 1 H, J = 0.9 Hz), 7.20 (td,1 H, J = 7.6, 0.9), 7.56 (m, 2 H), 7.76 (m, 1H), 8.10 (m, 1H); 13CNMR (CDCl,) 12.7,13.5, 21.8, 25.2, 39.9,48.8,49.0, 58.1, 97.2, 106.5, 126.4, 127.9, 129.3, 132.5, 133.0, 139.2, 146.7, 185.1, 205.7; IR (CClJ 2980, 1710, 1690, 1610, 1465, 1255, 1060 cm-'; mass spectral mol wt 330.1823, calcd 330.1833. Data for 42: 'H NMR (C6D8)6 0.84 (br t, 3 H, J = 7.0 Hz), 1.02 (br t, 3 H, J = 7.0 Hz), J = 7.6, 1.8 Hz), 7.26 (td,1 H, J = 7.6, 1.8 Hz), 7.78 (m, 1H); 13CNMR (CDCI,) 6 9.0, 14.0, 22.9, 25.6,28.7, 39.1,48.9,49.2, 49.4,53.5, 80.5, 97.9, 105.1, 125.6, 126.9, 128.4, 132.1, 132.5, 141.3, 198.0; IR (CClJ 3620, 3480, 1690, 1610, 1470, 1054 cm-'; mass spectral mol wt 348.1914, calcd 348.1938. Preparation of Dikcto Ketal 45. A solution of 2.1 mL (16 mmol) of nickel tetracarbonyl in 30 mL of ether was stirred under argon at -50 "C as 6.4 mL (13 mmol) of methyllithium-lithium bromide solution, 2.05 M in ether (Aldrich),was added over 5 min. After the dark red solution had been stirred at -50 "C for 1 h, a solution of 756 mg (3.26 mmol) of monoketal44 in 25 mL of THF was added dropwise over 10 min. The red reaction mixture was further stirred at -50 "C for 1.5 h and then diluted with 10 mL of HMPA. Allyl iodide (3.0 mL, 33.0 mmol) was added rapidly, and then the reaction mixture was warmed slowly to 23 "C and stirred for 14 h. The mixture was concentrated to ca. 20 mL by allowing argon to bubble slowly through at 35 "C for 2 h. The resulting slurry was poured into 300 mL of dilute aqueous ammonium chloride and extracted twice with 50-mL portions of ether and once with 50 mL of 2:l ether-dichloromethane. The combined extracts were washed with water (4X) and with brine (2X), then dried (Na2S04),filtered, and concentrated in vacuo to give an oily residue still containing HMPA and allyl iodide. Analytical TLC showed three components (ether; R f 0.29, 0.52, 0.58), the most polar of which was desired diketo ketal 44. The mixture was flashed chromatographed as a solution in benzene on 40 g of silica. Elution with 5 2 ether-petroleum ether separated 45 from the less polar contaminants, as a pale tan powder (559 mg, 54%). Two recrystallizations of a 30-mg sample (hexane-ethyl acetate, 2:l) gave 20 mg of colorless plates, mp 126-127 "C, showing spectra identical with that of the chromatographed material. 'H NMR (CDCl,) 6 7.65 (d, 1 H, J = 9.0 Hz), 7.38 (t, 1 H, J = 9.0 Hz), 7.08 (d, 1 H, J = 9.0 Hz), 6.0-5.4 (m, 1 H), 5.0-4.85 (m, 2 H), 4.4-4.0 (m, 4 H), 3.88 (s, 3 H), 3.55 (d, J = 9.0 Hz), overlapping with 3.4-2.25 (m, 4.3 H together), 2.25 (s, 3 H); IR (CHCl,) 3080 (s), 3000 (m), 2900 (m), 2840 (w), 1710 (s), 1690 (s), 1640 (w), 1585 (s), 1470 (s), 1440 (m), 1290 (s) cm-'. Anal. C, H. Preparation of Keto Hydroquinone 46. A solution of diketo ketal 45 (99.9 mg, 0.32 mmol) in 4 mL of dioxane was prepared under argon, cooled briefly, and stirred as 2 mL of degassed 6 N HC1 was added quickly. The reaction mixture was stirred as 23 "C for 3 days, during which time the color changed from pale yellow to cherry red. Analytical TLC showed clean conversion to the hydroquinone 46 (ether; Rf 0.38). The solution was poured into 20 mL of brine and extracted with one 40-mL and one 10-mL portion of 2:1 ether-dichloromethane. The combined extracts were washed twice with brine, then dried (Na2S04),filtered, and
J. Org. Chem., Vol. 50, No. 26, 1985 5573 concentrated in vacuo. Keto hydroquinone 46 was obtained as a dark, viscous oil, yield 88.3 mg (102%), contaminated with dioxane but otherwise pure by NMR and IR spectral analysis. This sample was used directly. 'H NMR (CDCI,) 6 9.12 (s, 1 H), 7.70 (d, 1 H, J = 9.0 Hz),7.27 (t, 1 H, J = 9.0 Hz), 6.71 (d, 1 H, J = 9.0 Hz), 6.2-5.7 (m, 1 H), 5.6-5.3 (br s, 1 H), 5.2-4.95 (2 H, allyl C=CH2), 4.00 (s, 3 H), 3.43 (dt, 2 H, J = 5.5, 1.5 Hz), 2.59 (3 H, s); IR (neat) 3400 (br, s), 3080 (w), 3020 (w), 2980 (m), 2950 (m), 2860 (w), 1685 (s), 1630 (s), 1610 (s), 1590 (m), 1500 (w), 1450 (s), 1400 (9); mass spectral mol wt 272.1029, calcd 272.1049. Preparation of Triol 47. To a solution of crude acetylnaphthohydroquinone 46 (88.3 mg, 0.32 mmol) in 5 mL of THF stirring under argon was added all at once 25 mg (0.66 mmol) of solid sodium borohydride. The mixture was stirred at 23 "C for 14 h, then cooled to 0 "C, and quenched by the dropwise addition of 0.3 mL of acetic acid. The resulting mixture was stirred at 0 "C for 15 min, diluted with 1mL of water, and cautiously saturated with potassium carbonate. The mixture was partitioned between 10 mL of degassed brine and 30 mL of degassed 2:l ether-dichloromethane. The aqueous layer was further extracted with one 10-mL portion of solvent. The combined organic layers were washed with degassed brine, then dried (Na2S0,), filtered, and concentrated in vacuo. Triol 47 (82.0 mg, 95%) was obtained as an amber solid. The solid was swirled with ether to give a white powder (mp 139.2-142 "C), but the crude product was used without further purification. 'H NMR (CDC1,) 6 9.60 (s, 1 H), 7.73 (d, 1 H, J = 8.0 Hz), 7.28 (t, 1 H, J = 8.0 Hz), 6.78 (d, 1 H, J = 8.0 Hz), 5.75-6.25 (m, 1 H), 5.3-4.95 (m, 4 H), 4.47 (br d, 1 H, J = 11 Hz),4.05 (s, 3 H), 3.56 (br d, 2 H, J = 5.0 Hz), 1.63 (d, 3 H, J = 6.5 Hz); IR (neat) 3350 (br, s), 3080 (w), 2990 (s), 2920 (m), 1630 (m), 1600 (m) 1580 (m), 1400 (vs), 1260 (vs); mass spectral mol wt 274.1198, calcd 274.1205. Preparation of Hydroxy Quinone 48. To a solution of triol 47 (487 mg, 1.88 mmol, from 1.71 mmol of 45) in 10 mL of dry, degassed methanol stirred under argon at 0 "C was added DDQ (403 mg,1.78 mmol), followed by solid potassium bicarbonate (188 mg, 1.88 mmol). The deep red reaction mixture was stirred at 0 "C for 1 h, then diluted with 20 mL of dichloromethane, and stirred for an additional 5 min. The resulting mixture was filtered through a short column of activity I alumina. Elution with dichloromethane and collection of all colored eluants gave on concentration crude quinone 48 (407 mg). Flash chromatography on 15 g of silica (twice; eluting with 4:l ether-petroleum ether) gave 48 (321 mg, 69% from 45) as a dark orange oil. Two recrystallization from ether-petroleum ether gave orange crystals: mp 76-78 OC; 'H NMR (CDCl,) 6 7.63-7.4 (m, 2 H), 7.13 (dd, 1 H, J = 8.5, 2.5 Hz), 6.C-5.58 (m, 1 H), 5.2-4.65 (m, 3 H), including apparent dq at 6 4.78 (1H, J = 11, 7 Hz); irradiation at 6 1.50 gives 6 4.8 (d, 1 H, J = 1 Hz), 3.92 (s, 3 H), 3.63 (d, 1 H, J = 11 Hz; collapses to s with irradiation at 6 4.71, 3.36 (dt, 2 H, J = 6, 1.5 Hz), 1.51 (9, 2 H, J = 7.0 Hz); IR (CHCl,) 3500 (br), 3080 (w), 3000 (m), 2930 (s), 2840 (w), 1650 (s), 1630 (s), 1570 (9) cm-'. Anal. C, H. Cyclization of 48 to the Pyrano Esters 49a and 49b. The reaction vessel was charged with 25.1 mg (0.092 mmol) of 2-al(48), 2.2 lyl-3-[(l-hydroxy)ethyl]-5-methoxy-l,4-naphthoquinone mg (0.009 mmol) of palladium chloride bis(acetonitrile)8and 28.7 mg (0.214 mmol) of copper(I1) chloride, and a stir bar was evacuated and vented to a carbon monoxide filled balloon, 5 times. Methyl alcohol (0.5 mL) was added, and the reaction mixture was stirred at 23 "C for 6 h. The reaction mixture was cooled to 0 "C and all volatile material was removed in vacuo. The dark red residue was triturated thoroughly with two 1-mL portions of benzene, and the triturates were filtered through a pipette of silica. Elution with ether and collection of all colored eluant gave on concentration the crude product as a dark red oil, yield 34 mg (112%). The crude product was flash chromatographed on 4 g of silica, loaded as a solution in benzene. Elution with 5:l ether-petroleum ether separated 49 as an orange foam, yield 26.9 mg (89%), a 3:2 mixture of trans/cis epimers. A similar preparation starting with 48 (152 mg, 0.56 mmol) gave 45 (3:2 mixture; 66% yield). Recrystallization from hot 2:l hexane-ethyl acetate gave 49a orange prisms of mp 144.5-145 "C. Anal. C, H. Spectral data match the published data (no melting point value given).3a Preparation of Diketo Ketal 50. The procedure to prepare diketo ketal 50 was identical with that used for 45. Thus mo-
5574
J . Org. Chem. 1985,50, 55744517
noketal44 (892 mg, 3.84 mmol) was allowed to react with the acyl nickel complex from 2.5 mL (19 mmol) of nickel tetracarbonyl and 15.4 mL (15.4 mmol) of propyllithium solution (1.0 M) in ether, in a mixture of ether (60 mL) and THF (25 mL), at -50 "C for 1 h. Dilution with 10 mL of HMPA and addition of 2.8 mL (31 mmol) of allyl iodide, followed by stirring at 23 "C for 14 h, gave conversion to three products (TLC (ether) Rf 0.43,0.48, 0.30). Isolation as before followed by flash chromatography (40 g of silica, eluting with 2:l ether-petroleum ether) provided the major component 50 as a yellow solid, yield 1.086 g (82%). Two recrystallizations from ethyl acetate-hexane (1:l) gave colorless prisms, mp 113.5-114 "C, identical with the chromatographed material by NMR and IR spectral analysis. 'H NMR (CDC13) 6 7.70 (dd, 1 H, J = 7, 2 Hz), 7.13 (dd, 1H, J = 8.0, 1.5 Hz), 7.40 (t, 1H, J = 7.0 Hz), 6.0-5.55 (m, 1 H), 5.2-4.9 (m, 2 H), 4.5-4.0 (m, 4 H), 3.88 (s, 3 H), 3.65 (d, 1 H, J = 6.5 Hz), 3.15-2.25 (m, 5 H), 1.7-1.35 (m, 2 H), 0.90 (t,3 H, J = 7.0 Hz); IR (CHCI,) 3080 (w), 3000 (m), 2970 ( s ) ,2840 (w), 1710 (s),1690 ( s ) ,1640 (w), 1590 ( s ) , 1480 (s), 1270 ( s ) an-'. Anal. C, H. Preparation of Keto Hydroquinone 51. Diketo ketal 50 was hydrolyzed exactly as described for 46. Thus a solution of 444 mg (1.29 mmol) of 50 in 12 mL of dioxane and 6 mL of 6 N HC1 was stirred at 23 "C for 2 days. Analytical TLC showed two components (2:l ether-petroleum ether; Rf 0.58 and 0.32), the more polar of which was desired hydroquinone 51. On a smaller scale, using recrystallized material, the less polar component was not observed. Isolation as before gave a labile, amber oil, yield 376 mg (97%),contaminated with a trace of dioxane but otherwise homogeneous by NMR spectral analysis. 'H NMR (CDC13)6 0.99 (t, 3 H, J = 6 Hz, CH,), 1.48-1.81 (m, 2 H, CHzCH2CH3),2.82 (t, 2 H, J = 6 Hz), 2.33 (dt, 2 H, J = 5, 1 Hz, CHZC=C), 3.96 (s, 3 H, OCH,), 4.95-5.25 (m, 2 H, allyl C=CHz), 5.72-6.15 (m, 1 H, allyl), 6.72 (dd, J = 6, 1 Hz, Ar), 7.30 (t, 1 H, J = 7 Hz, Ar), 7.70 (dd, 1H, J = 6 , l Hz, Ar); IR (CC14)3400 (m, OH), 2960 (m), 2930 (m), 1690 (m), 1450 (m), 1400 ( s ) , 1260 ( s ) , 1060 ( s ) cm-'; mass spectral mol w t 300.1365, calcd for CIsHzoO4300.1361. Preparation of Triol 52. To a solution of ketohydroquinone 51 (376 mg, 1.25 mmol) in THF (10 mL) under argon was added solid sodium borohydride (110 mg, 2.9 mmol) at 23 "C. The mixture was allowed to stir for 15 h, then diluted with 1.0 mL of water, and carefully saturated with potassium carbonate. The mixture was partioned between 10 mL of degassed brine and 30 mL of degassed 2:l ether/dichloromethane. The aqueous layer was further extracted with one 10-mL portion of 2:l ether/dichloromethane. The combined organic solutions were washed with degassed brine, dried (Na,SO,), filtered, and concentrated in vacuo. The crude triol 52 was obtained as an amber oil, 369 mg, 98%. 'H NMR (CDC1,) 6 9.5 (s, 2 H). 7.7 (br d, 1 H, J = 8.0 Hz),
7.25 (br t, 1 H, J = 8.0 Hz), 6.73 (br d, 1 H, J = 8.0 Hz), 6.2-5.7 (br m, 1 H), 5.3-4.8 (m, 3 H), 4.03 (s, 3 H), 4.2-3.8 (m, 2 H), 3.54 (br d, 1 H, J = 7.0 Hz), 2.30-0.8 (m, 7 H); IR (neat) 3350 (br, s), 3080 (w), 2970 ( s ) ,2870 (m), 1630 (w), 1610 (m), 1580 (m), 1450 ( s ) , 1380 (vs), 1250 (vs). Preparation of Hydroxy Quinone 53. The crude triol 52 (312 mg, 1.03 mmol) was stirred in a mixture of DDQ (224 mg, 0.99 mmol) and potassium bicarbonate (117 mg, 1.17 mmol) in 10 mL of methyl alcohol under argon at 0 "C for 1.0 h. Dilution with dichloromethane and filtration through alumina gave crude naphthoquinone 53 as an orange oil, 242 mg. Flash chromatography on silica gel (15 g; elution with 4:l ether-petroleum ether) gave pure 53 as an orange oil, 134 mg, 45% yield overall from 50. 'H NMR (CDCl,) 6 7.8-7.5 (m, 2 H), 7.25 (dd, 1 H, J = 8.0, 2.5 Hz), 6.1-5.6 (m, 1 H), 5.3-5.0 (m, 2 H),4.9-4.6 (m, 1 H), 4.00 (s, 3 H), 3.72 (d, 1 H, J = 11 Hz), 3.38 (br d, 2 H, J = 3.5 Hz), 2.2-1.3 (m, 4 H), 0.95 (t, 3 H, J = 6.0 Hz); IR (neat) 3500 (br, s), 3080 (w), 2960 ( s ) ,2880 (m),2840 (m), 1650 (d, vs), 1620 ( s ) ,1590 (vs), 1470 (vs), 1450 (vs), 1280 (vs) cm-'; mass spectrum, m/e 300 (M+, 58%), 282 (30), 271 (28), 257 (loo), 239 (33), 229 (19), 214 (12). Preparation of Pyrano Ester 54a,b. The hydroxynaphthoquinone 53 (174 mg, 0.58 mmol) was stirred with a mixture of bis(acetonitri1e)palladium dichloride (14 mg, 0.058 mmol), anhydrous cupric chloride (171mg, 1.27 mmol), and methyl alcohol (3 mL) under carbon monoxide (1.0 atm) for 3.3 h and gave essentially one component detected by analytical TLC (ether on silica gel, Rf 0.35). The mixture was concentrated at oil pump pressure, triturated with benzene ( 5 mL), and purified by flash chromatography on silica gel ( 5 9). Elution with 7:2 ether-petroleum ether gave as the main component an orange viscous oil, 144 mg (70%). Analysis by HPLC (Poracil column, 8:l hexane-ethyl acetate, 5 mL/min; R, trans 8.85 mL, R, cis 10.3 mL) indicated a mixture of isomers in the ratio 75:25 later identified as the trans/& mixture 54a,b. The chromatographed material was crystallized from 3 mL of warm 3:l hexane-ethyl acetate to provide pure 54a as dark orange needles, mp 128-133 "C. Recrystallization gave the analytical sample, mp 134-136 "C. 'H NMR (CDC1,) 6 7.7-7.4 (m, 2 H), 7.13 (dd, 1H, J = 7.5, 2.5 Hz), 4.80 (br t, 1 H, J = 5.0 Hz), 4.4-4.1 (m, 1 H), 3.97 (s, 3 H), 3.70 (s, 3 H), 2.85-2.58 (m, 3 H), 2.22 (ddd, 1 H, J = 17.0, 10.0, 1.0 Hz), 1.9-1.2 (m, 4 H), 0.95 (t,3 H, J = 6.5 Hz); IR (CHC1,) 3030 (m), 2960 (m), 2880 (m), 2840 (m), 1735 ( s ) , 1660 (vs), 1590 ( s ) , 1470 (m), 1440 ( s ) , 1280 (vs) cm-'. Anal. C, H. The cis isomer 54b was previously ~haracterized.~"
Acknowledgment. We acknowledge financial support in the form of a research grant (NIH GM 31352) and NIH postdoctoral fellowships to E.J.S. and W.W.
Structural Effects in Solvolytic Reactions. 51. Examination of the Differences in the Behavior of Secondary and Tertiary U-Shaped Bicyclic Derivatives toward Solvolysis Herbert C. Brown,* Irvin Rothberg,l* and J. Chandrasekharanlb Richard B. Wetherill Laboratory, Purdue Uniuersity, West Lafayette, Indiana 47907 Received May 28, 1985 The solvolyses (acetolysis) of secondary bicyclic tosylates such as cis-bicyclo[3.3,0]oct-2-yland 5,6-endo-trimethylene-&norbornyl and -9-norbomyl proceed with low exo/endo rate ratios (
